The present invention relates to subterranean treatment operations. More particularly, the present invention relates to improved treatment fluids and methods of using such improved treatment fluids in subterranean formations.
The process of drilling a well bore in a subterranean formation typically requires the use of a treatment fluid referred to as a “drilling fluid.” During the drilling process, the drilling fluid passes down through the inside of a drill string, exits through a drill bit, and returns to a drill rig through an annulus between the drill string and the walls of the well bore. The circulating drilling fluid, inter alia, lubricates the drill bit, carries drill cuttings to the surface, and balances the formation pressure exerted on the well bore.
To prevent undesirable leak-off of the drilling fluid into the formation, drilling fluids often may be formulated to form a fast and efficient filter cake on the walls of the well bore. The filter cake often comprises an inorganic portion (e.g., calcium carbonate), and an organic portion (e.g., starch and xanthan). The filter cake generally is removed before the production of hydrocarbons from the formation. Conventional methods of removal have involved contacting the filter cake with one or more subsequent cleanup fluids (e.g., an acid) that are formulated to degrade either the inorganic portion or the organic portion of the filter cake. These methods have been problematic, however, because conventional cleanup fluids tend to degrade the filter cake unevenly, which may result in premature leak-off of the cleanup fluid into the formation through “pinholes” in the filter cake, before the entirety of the filter cake has been degraded. This is undesirable, because it may leave the majority of the filter cake intact within the well bore, thereby delaying the onset of hydrocarbon production from the formation, and necessitating repeated cleanup efforts until the filter cake eventually may be removed to a desired degree.